Coloration of materials



is either a mordant Patented June 2, 1936 UNITED STATES PATENT OFFICE 2,042,802 ooLoaa'rIoN' OF MATERIALS Herbert Platt, Cumberland, Md" assignor to Celanese Corporation of America, a corporation of Delaware No Drawing. Application January 26, 1934, Serial No. 708,411

20 Claims.

a process whereby materials made from or con-:

taining organic derivatives of cellulose may be dyed with a bottom color that is a natural' chromed dye and then topped with a color that dye, a direct dye, another natural chromed dye, or any other dye having an afiinityfor the organic derivative of cellulose. Another object of the invention is to obtain the improved products resulting from this invention. Other objects of this invention will appear from the following detailed description.

'Heretoiore great difiiculty has been experienced in successfully dyeing deep colors on fabrics made of organic esters of cellulose with natural dyes. One of the great sources of annoyance was the production of ofi shades and unexpected shades.

t I have found a process whereby such fibres can be colored to a desired shade successfully and economically by the natural dyes. This makes possible the application of a large class of dyestufis to the dyeing of such fibres that heretofore could not be employed with safety. For,

example, organic derivatives of dyed safely with logwood.

' Textile materials dyed according to this invention are not materially weakened nor is there a material change in lustre, hand, or other textile properties.

By the method of this invention textile materials may be dyed a thin shade with a natural dye to give a gray or light bottom color that can then be topped up to shade with direct dyeing cellulose maybe dyestufis which is considerably cheaper than attempting to obtain deep colorations free from acid fading by the use of direct dyeing dyestuffs alone. The natural dyes, however, may be employed alone to give deep colors or they may form a deep colored bottom which may be topped with another natural dye to produce the desired shade.

According to this invention, I treat textile materials with a natural dyestufi which is raisedto the color desired and made fast by a treatment with a bichromate and an aid such as an organic acid, a salt of an organic acid or any other aid which is a mild reducing agent.

This invention is applicable to the dyeing of any textile material and especially those made at .leastin part of organic derivatives of cellulose such as organic esters and ethers of cellulose. Examples'of organic esters of cellulose are cellulose acetate, cellulose formate, cellulose propionate and cellulose butyrate, while examples of organic ethers of cellulose are ethyl cellulose,

methyl cellulose and benzyl cellulose. Fabrics and yarns which contain mixtures of difierent types of fibres or filaments may be dyed or cross dyed according to this invention. Thus, yarns and fabrics containing fibres or filamentsjof organic derivatives of cellulose and wool, or organic derivatives of cellulose and silk, or organic derivatives of cellulose and regenerated cellulose or organic derivatives of cellulose and other fibres or filaments may be dyed according to this invention.

The dyeing may be performed in the yarn, fabric or garment stage of the processing of textiles. Yarn may be dyed as hanks or in packages. The yarn may be woven, warp knitted, circular knitted or otherwise processed to fabrics and then dyed or such fabrics may be further processed to garments and wearing apparel prior to dyeing.

This invention is applicable to yarns that, if synthetic, may contain incorporated therewith effect materials suchas pigments'and filling materials, fire retardants,plasticizers,sizes and lubricants. Where, however, such pigments and filling materials as titanium dioxide and antimony triom'de are incorporated with the yarn they have the effect of modifying the resulting color. Thus, when dyeing with logwood, their presence 'throws the resulting color to the blue side of cutch, etc. Thematerial to be dyed may be placed in a bath about 30 times its own weight of a solution of the natural dye in water. The natural dye may be employed in the solution in from 1 to 10 percent depending upon whether the material is to be dyed as a complete color or dyed as a bottom color. This bath is maintained at to 100 C., preferably about C.. and the material is allowed to remain therein for from 20 C. depending upon the material treated. For

organic derivatives of cellulose being, dyed with logwood temperatures of 60 to 100 C., particularly 70 to C. are preferable. The bath may contain from 1 to 4% of the dichromate salt.

The bath may also containaids such as oxalic acid or sodium orpotassium oxalate or mixtures of these. It is found-that these aids efiect some control over the shade of color produced and its fastness to light. Thus, in dyeing with logwood, the presence of an oxalate controls the blueness of the shade and the fastness to light. The percentage of oxalate that may beemployed in the bath is betweenl and. 3%.

Thus, a good black is obtained on cellulose acetate by dyeing with 10% solution of hamatein at 80 C. for 1 hour and then chroming with a solution of 2% sodium bichromate and 1.5% sodium oxalate at 75 C. for 30 minutes, rinsing and soaplng.

The length of time that dyes, such as logwood, are chromed must be ascertained for each particular fabric material, for when logwood is underchromed (chromed too little) or over-chromed (chromed too much) lack of light-fastness results; the logwood in the first case turns a reddish brown, whilst in the latter case it turns yellower or greener when exposed to light.

There may be added a small percentage of magnesium sulfate to the dye bath. This salt gives more light fastness to the dye. The presence of various salts also controls the color imparted by such dyes as chromed natural dyestufls. Thus, in dyeing with a low percentage of logwood as the dyeing material, the presence of magnesium sulphate gives a greyish navy blue, calcium chloride gives a greyish navy blue, calcium hydroxide gives a pearl grey, calcium acetate gives a blue which becomes lighter the greater amount of salt used, while lead acetate gives a, greenish.

to yellowish black.

In dyeing cellulose acetate material with logwood, it is found that using an insufiicient amount of sodium bichromate at too low a temperature causes a logwood black that turns a reddish brown on exposure to light, whilst 'an excessive amount of sodium bichromate at too high a temperature causes a greening of the logwood black. The optimum conditions for a light fast black is a t'reatment for 20 to 40 minutes with a solution containing 1.5 to 2.5% sodium bichromate maintainedat 60-70' C.

The temperature at which logwood is applied has no appreciable effect on the shade or lightresisting properties, except that the higher the temperature, the greater the depth of color obtained.

' When fabrics or yarns of subdued lustre, caused either by the presenceof finely divided pigments therein or by delustering the same (as by treat-' ing cellulose acetate material with hot aqueous soap solutions), are treated by this invention, it is possible to obtain blacks or other dark shades of subdued lustre, whereas bright lustreis obtained by prior methods. Logwood grey or blue may be topped by a second dyeing with logwood I to light.

According to the method of this invention, the 6 natural dyestuffs readily lend themselves to the printing of fabrics. Thuaorganic derivatives of cellulose and silk or mixtures or these may be successfully printed with a paste containing 10 parts of haamatein, 5 parts ofglycerine, 25 parts of glucose, British gum or tragacanth gum, and 60 parts of water. After printing by such means as printing presses, brushing or spraying over stencils and like means, the printed fabric is steamed for about 15 minutes at about 5 lbs. 15 pressure then chromed in a. 2% solution of sodium bichromate and 1 /2% sodium oxalate, or a similar chroming solution after which .theyare rinsed and soaped. The color imparted is a deep black.

Instead of treating the textile material in a bath ofthe dye liquor, such dye may be applied to the fabric by padding or other mechanical impregnation, and then fixed either by heating or by batching for a substantial period, after which the fabric may be treated with the chromingbath. a

As an aid to the chromate salt in placeof oxalic acid or its salts there may be employed any other mild reducing agent, such as ammonium thiocyanate or alkali sulphites. The ammonium sulphocyanide may be used alone or in connection with the oxalicacid or its salts. These materials effect both the trueness of color and its fastness As a means of further describing the invention there are given the following examples.

Example I Cellulose acetate fabric is dyed by treating for 1 hour with a /2% solution of logwood crystals at 80 C., and then chromed with a 2% solution of sodium bichromate having 1%% of sodium oxalate therein. The chrome bath ismaintained at 60 and the treatment is for 30 minutes.

A blue grey shade is obtained. This grey may be used as such or used as a bottom color to be topped with a direct dye, another logwood dyeing or another natural dye. 50

Example II The material dyed or bottomed by Example I is topped with a mixture of direct dyes of yellow,

orange and red colors. The shade is thus brought 55 up to a dead black.

Example III Example IV A material of cellulose acetate is dyed with a 70 solution of 10% logwood for 1 hour at 80 C., rinsed, and'treated with 2% sodium bichromate and l 2% sodium oxalate solution for 30 minutes at 70-75 C.,. rinsed and soap scoured. 7

Percent solugg tion log- Na Cr 0 Shade obtained wood 2 2 7 and an aid 0. 1 1. 0 Light neutral grey. 0.2 1. 0 Pale grey. 0. 25 l. 0 Slate grey. 0. O 1. 0 Dark grey. 0. 75 1. 0 Do. 1. 0 l. 0 Dark greyish blue.

1. 25 2. 0 Dark greyish black. 1. 50 2.0 Do. 1.75 2. O Yellowish black. 2.0 2.0 Black. 3 2 Deep black.

There is apparently no difference as to which of the alkali metal. salts of either the chromic acid or oxalic'acid are employed.

Having described the invention, what I desire to secure by Letters-Patent is:

1. The process of imparting color to textile materials which comprises applying thereto a natural mordant dyestuff requiring an after treatment with a salt of a chromic acid, an alkali salt of a chromic acid and a compound selected from the group consisting of oxalic acid,- alkali salts of oxalic acid, ammonium thiocyanate and alkali sulphites.

2. The process of imparting color to textile ma- T terials comprising organic derivatives of cellulose which comprises applying thereto a natural mordant dyestufi requiring an after-treatment with a salt of a chromic'acid, an alkali salt of a chromic acid and a compound selected from the group consisting of oxalic acid, alkali salts of oxalic acid, ammonium thiocyanate and alkali sulphites.

3. The process of imparting color to textile materials comprising cellulose acetate which comprises applying thereto a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid, an alkali salt of a chromic acid and a compound selected from the group consisting of oxalic acid, alkali salts of oxalic acid, ammonium thiocyanate and alkali sulphites.

4. The process of imparting color to textile materials comprising synthetic filaments of a cellulose derivative containing finely divided pigments therein which comprises applying thereto a natural mordant dyestufi requiring an aftertreatment with a salt of a chromic acid, a chromic acid alkali salt and a compound selected from the group consisting of oxalic acid, alkali salts of oxalic acid, ammonium thiocyanate and the alkali sulphite salts.

5. The process of imparting color to textile materials comprisingfilaments of cellulose acetate containing finely divided pigments therein which comprises applying thereto, a natural mordant dyestufi requiring an after treatment with a salt of a chromic acid, an alkali salt ,of chromic acid and a compound selected from the group consisting of oxalic acid, alkali salts of oxalic acid, ammoniurn thiocyanate and the alkali sulphite salts.

6. The process of imparting color to textile materialswhich comprises applying thereto a natural mordantdyestufi requiring an after-treatment with a salt of a chromic acid and chroming same with an alkali dichromate in the presense of an alkali oxalate.

7. The process of imparting color to textile materials comprising organic derivatives of cellulose which comprises applying thereto a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid and chroming same with an alkali dichromate in the presence of an alkali oxalate.

8. The process of imparting color to textile materials comprising cellulose acetate which comprises applying thereto a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid and chroming same with an alkali dichromate in the presence of an alkali oxalate.

9. The process of imparting color to textile materials comprising organic derivatives of cellulose Which comprises applying thereto a bottoming color of a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid, chroming same-with an alkali dichromate in the presence of alkali oxalate and then applying a topping color.

10. The process of imparting color to textile materials comprising cellulose acetate which comprises applying thereto a bottoming color of a natural mordant dyestufi requiring an aftertreatment with a salt of a chromic acid, chroming same with an alkali dichromate in the presence of alkali oxalate and then applying a topping color.

11. The process of imparting color to textile materials comprising organic derivatives of cellulose which comprises applying thereto a bottoming color of a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid, chroming same with an alkali dichromate in the presence of an alkali oxalate and then applying a natural dye as a topping color and chroming same.

12. The process of imparting color to textile materials comprising cellulose acetate which comprises applying thereto a bottoming color of a natural mordant dyestufi requiring an aftertreatment with a salt of a chromic acid, chroming same with an alkali dichromate in the presence of an alkali oxalate and then applying a natural dye as a topping color and chroming same.

13. The process of imparting deep colorations to textile materials while retaining asubdued lustre comprising applying to textile materials of subdued lustre comprising derivatives of cellulose a logwood dye, chroming same with a chromate in the presence of a substance selected from the group consisting of oxalic acid, alkali salts of oxalic acid, ammonium thiocyanate and alkali sulphite.

' 14.'The process of imparting deep colorations to textile material while retaining a subdued materials comprising organic derivatives of cellulose which comprises applying thereto .logwood from an aqueous bath and chroming the logwood treated textile materials with an aqueous bath containing an alkali dichromate and an alkali oxalate. i

1'7. The method of imparting color to textile materials which comprises printing the material with a paste comprising a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid, steaming the prinwtile material and chroming in a solution comprising an alkali dichromate and. an alkali oxalate.

18. A textile material colored with a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid chromed with a so= lution containing an alkali dichromate and an alkali oxalate.

19. A textile material colored with a natural mordant dyestufi requiring an after-treatment with a salt of a chromic acid chromed with a solution containing an alkali dichromate anda compound selected from the group consisting of oxalic acid, alkali salts of oxalic acid, ammonium thiocyanate and alkali sulphite salts.

-20. A textile material colored with logwood chromed with an alkali dichromate and an alkali oxalate.

HERBERT PLATT. 

